DE102014221871A1 - Fluid and fuel pump system - Google Patents

Abstract

There is provided a fluid pump system (10) comprising a first fluid pump assembly (100) configured to receive and deliver fluid via a first fluid supply line (114) via a first fluid discharge (116) and a second fluid pump assembly (200) is to receive a fluid via a second fluid supply line (214) and deliver via a second fluid discharge line (216). The first fluid pump assembly (100) comprises: a first pumping device (105) having a first pumping unit (110) and a first pumping motor (120), the first pumping motor being coupled to the first pumping unit (110) such that the first pumping motor is the first pumping motor (110) can drive first pump unit; a power source (130) for powering the first pump motor (120); and a control unit (140) configured to read in a target value for a fluid pressure to be supplied by the first pump device (105) and to determine a current corresponding to the target value of the fluid pressure to be supplied to the first pump motor (120) at a given pump motor speed and to drive the power source (130) to output the detected current to the first pump motor (120).

Description

The invention relates to a fluid pump system, a method for operating a fluid pump system, and a vehicle having such a fluid pump system.

Fluid pumps in the form of fuel pumps are commonly used in vehicles to pump or convey a fuel, which is usually held as fluid, from a fuel tank to a drive unit, which in this case is usually designed as an internal combustion engine.

As fuel pumps are basically all pumps in question, which are designed to pump a fluid. A fuel pump for a vehicle is usually designed to supply the fuel with a predetermined or specifiable fuel pressure to the internal combustion engine. Furthermore, a fuel pump is usually designed to deliver a predeterminable volume flow of the fuel, so a certain amount of fuel per unit time (usually in liters per hour).

Conventional fuel pumps have a pump stage, which may also be referred to as a pump unit, and a pump motor. The pump motor is coupled to the pump stage so that the motor moves the pump stage and pumping the fuel through this movement. The delivered volume flow of the fuel pump is usually proportional to the speed of the pump motor.

The pump stage is coupled via a fuel supply line with the fuel tank or is located in the fuel tank and is coupled via a fuel discharge to the internal combustion engine. In order to achieve a predeterminable fuel pressure in the fuel discharge, usually a pressure sensor is arranged so that the fuel pressure is detected. The detected fuel pressure is used to vary the speed of the pump motor when the fuel pressure in the fuel delivery is to be changed.

Usually, a speed-controlled system is used as a pump device, since the speed of the pump motor is proportional to the volume flow. If the speed increases at a constant volumetric flow, the pressure in the fuel discharge increases as well. The behavior in individual cases depends on the so-called pressure stiffness of the pump stage.

It may be considered as an object of the invention to provide a fluid pump system and a method for controlling a fluid pump system, which are characterized by a simplified control of the fluid pump system and a more economically advantageous implementation.

According to a first aspect of the invention, a fluid pump system is disclosed. The fluid pump system includes a first fluid pump assembly configured to receive fluid via a first fluid supply line and dispense via a first fluid discharge and a second fluid pump assembly configured to receive fluid via a second fluid supply line and dispense via a second fluid discharge. The first fluid pump arrangement has a first pump device, a power source and a control unit. The first pump device includes a first pump unit and a first pump motor, wherein the first pump motor is coupled to the first pump unit so that the first pump motor can drive the first pump unit. The power source is designed to power the first pump motor. The control unit is designed to read in a setpoint value for a fluid pressure to be supplied by the first pump device and to determine a current for the first pump motor that corresponds to the setpoint value for the fluid pressure to be supplied and to control the energy source such that it determines the determined current intensity outputs the first pump motor.

Such a fluid system may also be referred to as a multi-pump system. In particular, the first and second fluid pump arrangement are connected in parallel with each other and are operated synchronously. Alternatively, the two fluid pump assemblies may also be serially connected, i. h., A fluid pump assembly is connected downstream of the other fluid pump assembly. In order to prevent the fluid pump assembly due to different tolerances and behaviors, which can lead to a non-uniform pumping behavior, to adversely affect the pumping capacity of the fluid pump system, the fluid pump system is configured so that both fluid pump assemblies promote an equivalent amount of fluid, so a substantially have the same volume flow of the fluid in the respective fluid discharge. It should therefore be prevented in particular that the pumps deliver a different volume flow, z. B. 20 liters / hour, the first fluid pump assembly and 100 liters / hour, the second fluid pump assembly, since in such a case in a parallel operation of the two fluid pump assemblies, the pumping power from a fluid pump assembly essentially runs into the void.

The first fluid pump arrangement is constructed so that it waives a Pressure sensor in the fluid discharge allows. The adjustment of the fluid pressure in the fluid discharge takes place via an adaptation of the pump current and via the rotational speed of the pump motor. By eliminating the pressure sensor, fluid pump systems can be constructed more economically.

It should be noted that the fluid pump system can also have more than two fluid pump arrangements, so that several fluid pump arrangements are connected in succession or in parallel or in mixed forms (parallel connection of series circuits or vice versa).

The pump motor may be, for example, a DC motor or a synchronous motor, the latter, for example, in the embodiment as a permanent magnet motor with, for example, permanent magnet rotor, which is operated with three-phase current.

The fluid pump system can be, for example, a system for pumping fuel for a vehicle, a hydraulic pump or a coolant pump for a cooling circuit.

It should be noted that reference to the "fluid pressure" below always means the fluid pressure in the corresponding first or second fluid discharge unless explicitly stated otherwise.

The setpoint for the fluid pressure can be specified by an external unit, for. B. from an internal combustion engine or a component of the internal combustion engine, such as. As an engine control unit or an exhaust gas control unit, which is supplied by the fluid pump unit with fluid or from another unit in a vehicle.

The energy source is in particular designed to output a specifiable current to the pump motor. The power source is a power source in one embodiment.

The pump device may have a speed determination unit, which is designed to determine the speed of the pump motor and to forward on request, in particular to the control unit.

The control unit and the pump device may be spatially separated from each other and mounted, for example, in a vehicle as separate mounting units. The communication or data transmission between the pump device and control unit can via a data transmission path, for. B. via a bus system such as CAN done.

According to one embodiment of the invention, the first fluid discharge is coupled to the second fluid discharge, so that these two fluid discharges open into a common discharge. In this case, the first fluid pump arrangement is coupled via a first check valve to the common discharge line and the second fluid pump arrangement is coupled to the common discharge line via a second check valve.

This structure describes the so-called. Parallel operation of two fluid pump assemblies. In this operation, either both fluid pump assemblies can be used simultaneously or only one fluid pump assembly, e.g. B. in alternating sequence or as a redundant system operated. The check valves prevent a fluid pump assembly from pumping fluid into the fluid drain of the other fluid pump assembly, thus causing a flow in an undesired direction.

According to a further embodiment of the invention, the second fluid pump arrangement comprises a second pump device having a second pump unit and a second pump motor, wherein the second pump motor is coupled to the second pump unit so that the second pump motor can drive the second pump unit. The power source is designed to power the second pump motor. The control unit is designed to read in a target value for a fluid pressure to be supplied by the second pump device and to determine a current for the second pump motor corresponding to the target value for the fluid pressure to be supplied and to control the energy source such that it applies the determined current intensity outputs the second pump motor.

It should be noted that the first fluid pump arrangement can basically be coupled to a second fluid pump arrangement, which has a pressure sensor in the second fluid discharge. However, in this embodiment, the second fluid pump assembly is similar in construction to the first fluid pump assembly and does not have a pressure sensor in the fluid drain. In this regard, the statements regarding the first fluid pump arrangement apply mutatis mutandis to the same for the second fluid pump assembly.

The second fluid pump assembly and the first fluid pump assembly may be co-powered by the same power source and controlled by the same controller. Alternatively, however, both fluid pump assemblies may each have their own energy sources and control units.

According to a further embodiment, the fluid pump system further comprises a storage unit, which is designed to store a current-speed characteristic of the first pump motor, wherein the current-speed characteristic corresponds to a fluid pressure supplied by the first pump unit.

In other words, a value pair which gives on the current-speed characteristic leads to a fluid pressure caused by this characteristic. The memory unit may be configured to permanently store the characteristic values for read access or else so that the characteristics may be adjusted if the pump device assumes changed operating characteristics over time. The storage unit may be configured to obtain a map field from a configuration unit which writes the characteristics in the storage unit. This data can be transmitted by cable or without line between the configuration unit and the storage unit.

According to a further embodiment of the invention, the memory unit is designed to store a plurality of current-speed characteristics of the first pump motor, wherein each of the current-speed characteristics corresponds to a respective supplied from the first pump unit fluid pressure.

The characteristic curve is an isobaric characteristic (pressure-constant form of representation or pressure lines) in a diagram which plots the current intensity (usually indicated in amperes) over the pump motor speed (usually stated in revolutions per minute) and a specific fluid pressure in the Fluid discharge corresponds. The characteristic curve runs in such a way that the specific fluid pressure in the fluid discharge can be set at different constellations of the current intensity and the rotational speed, ie. that is, there is not a certain point in the diagram for a fluid pressure, but a plurality of pairs of points (characteristic).

The reading of the current from a characteristic makes it possible that the current must not be determined algorithmically in a complex computation. The current intensity is determined by accessing a stored characteristic, in particular read out from a map.

Several characteristic curves for a multiplicity of different fluid pressure values can be provided in the fluid discharge. Depending on the desired or predetermined fluid pressure in the fluid discharge, the corresponding characteristic curve is accessed in order to determine the required current intensity for the pump motor.

According to a further embodiment of the invention, the control unit is designed to determine the pump motor speed of the first pump motor and to control the energy source so that it adjusts the current with which the first pump motor is operated according to the characteristic, so that the setpoint for the of the adjusted or maintained fluid pressure supplied to the first pump device.

When the current intensity is adjusted, the pump motor speed usually changes, with the result that the fluid pressure and the volume flow of the fluid in the fluid discharge also change as a result. This may require monitoring the pump motor speed to make a corresponding readjustment of the current so that a current / speed value pair is selected on a characteristic which is on the isobaric characteristic corresponding to the predetermined fluid pressure.

In other words, when a new target pressure for the fluid pressure is specified, starting from the current pump motor speed, a current is read from the characteristic curves, which causes the desired fluid pressure with the current pump motor speed. Since at a changed pump motor speed, which can occur as a result of the changed current, the current (again) may require a change to reach the target pressure, in this embodiment, the fluid pressure approaches the target pressure iteratively, ie in several successive steps. In each of these steps, an adjustment of the current depending on the characteristics and the desired fluid pressure may be required until the target pressure is reached.

In other words, the fluid system as described herein may be summarized as follows. The fluid system allows operation of a multi-pump system in an embodiment without pressure sensors in the fluid drain. In each path or to each fluid pump arrangement, the delivery volume and the fluid pressure in the fluid discharge can be easily adjusted without having to determine the fluid pressure with a complex pressure detection unit. The delivery volume and the speed of the individual fluid pump assemblies can be adapted to the respective working conditions.

The fluid pressure in both fluid outlets is substantially the same, so that both fluid pump arrangements have a delivery volume or make a contribution to the volume flow in the common discharge. In particular, a maximum allowable differential pressure between the first fluid discharge and the second fluid discharge may be an opening pressure of one or both Non-return valves correspond. For this reason, the information about the fluid pressure in both fluid discharges may be required.

In a fluid pump system as described herein, various modes of operation are possible. In a parallel operation, the fluid pump assemblies operate simultaneously and throughout the operating time of the fluid pump system. In a downstream operating mode, one pump can always be in operation (continuous operation) and a second pump is switched on at peak load (peak load operation). The downstream operation can also be modified and one pump takes over the continuous operation of the other pump. In a cascade operation, the first pump can be operated at a fluid pressure of 5 bar and the second pump at a fluid pressure of 4.5 bar. If the fluid pressure in the fluid discharge drops below 4.5 bar (eg due to large quantities), the second pump will help to achieve the required volume flow.

Dispensing with pressure sensors reduces the cost of such a fluid pump system. An uneven flow and delivery volume distribution to the fluid pump assemblies can be detected and compensated. For each pump assembly, a separate pressure control system is provided, and in particular both fluid pump assemblies behave independently of each other. Decisive is the fluid pressure in the common fluid discharge, which is to be regulated here. In the case of the takeover operation, it is possible to recognize when a fluid pump arrangement actually and effectively contributes to the delivery volume. The control unit as described herein assists in maintaining fluid pressure in the common fluid drain.

In another aspect, a method of driving a fluid pumping system is described as described herein. The method comprises the following steps: presetting a desired value for a fluid pressure in the first fluid discharge; Determining a current value which is associated with a pump motor speed of the first pump motor and the predetermined setpoint value for the fluid pressure corresponds; and outputting the readout current to the first pump motor of the first fluid pump assembly.

That the current is associated with a pump speed and corresponds to a setpoint for the fluid pressure means, for example, that a value pair of current and pump motor speed lead to the predetermined fluid pressure in the fluid discharge, thus bring about this by the current and the pump motor speed.

The method is particularly suitable for the operation of a sensorless pressure control system, that is for a fluid pump assembly without pressure sensor in the fluid discharge. The method makes it possible to control a fluid pump arrangement so that a pump unit is guided in order to achieve a desired fluid pressure under different working conditions. For a recourse to a variable speed pump device is not necessary, so that a cost for its production and control is eliminated or reduced by the method described here. The method is based on the finding that there is a causal relationship between the current intensity, the rotational speed and the fluid pressure. On the sole regulation of the current intensity of the pump motor, a fluid pressure can be set by resorting to isobaric pressure curve characteristics. The regulation of the current intensity can be done either by a variable current source or by the determination or measurement of the current of the pump motor and adjustment of the current and the speed to the desired conditions, that is, to the desired fluid pressure.

The current is determined based on the currently applied pump speed and the desired fluid pressure. The current intensity can be determined directly with the aid of an isobaric characteristic current intensity over speed at a given fluid pressure. There is an isobaric characteristic for any desired fluid pressure, and for any pumping speed that occurs, there is a suitable current rating for the current regulator, i. H. the current supplied to the pump motor. In particular, during operation of the fluid pump assembly, the resulting engine speed may not be critical. Decisive for the control is solely the current, which is set via a control unit.

In an alternative embodiment, the flow of the pump motor may also be used alone to achieve fluid pressure in the fluid drain. The current and voltage of the pump motor, both known, are used to determine the power transferred to the pump motor, e.g. For example, 20 watts. By means of an estimate, the pressure in the fluid discharge can be determined based on the decrease volume of the fluid in the fluid discharge. In this case, the efficiency of the pump motor can be taken into account.

According to one embodiment of the invention, the determination of the current value, which is associated with the pump motor speed of the first pump motor, comprises the following step: reading the current from a characteristic which corresponds to the predetermined setpoint for the fluid pressure.

According to another embodiment of the invention, the method further comprises the steps of monitoring the pump motor speed of the first pump motor and adjusting the current magnitude according to the characteristic so that the setpoint for the fluid pressure in the first fluid discharge is set or maintained.

According to a further embodiment, the method further comprises the steps of determining a respective pump motor speed-current characteristic for a plurality of desired values of the fluid pressure in the fluid discharge and providing the characteristics thus determined in order to read out the current intensity associated with a pump motor speed at a predetermined desired value of the fluid pressure ,

These steps are to initially determine the dependencies and correlations between the fluid pressure, the pump motor current, and the pump motor speed. It can be determined for each desired fluid pressure (eg 2 bar, 3 bar, 4 bar, 5 bar, 6 bar) a characteristic which is plotted as the current of the pump motor over the speed of the pump motor. The characteristic curves can be determined at intervals of 1 bar or more or less than one bar and kept for later use. A lower and upper limit for the desired values of the fluid pressure is based on the customer of the fluid, that is, on the needs of an internal combustion engine, which is supplied with fuel from the fluid pump assembly.

According to another aspect of the invention, there is provided a vehicle having a fluid pumping system as described herein, wherein the fluid pumping system is configured as a fuel pumping arrangement.

The fuel tank is in particular a fuel tank, which is a fluid, for. As gasoline or diesel contains.

The vehicle is, for example, a motor vehicle, such as a car, bus or truck, or even a rail vehicle, a ship, an aircraft, such as a helicopter or airplane. Such a vehicle is characterized in particular by the fact that it has an internal combustion engine, which is used as a drive unit and is operated with a fluid.

According to one embodiment of the invention, the fluid pump system is coupled to a fuel tank and is designed to deliver a fuel contained in the fuel tank to a drive unit of the vehicle.

According to one embodiment of the invention, the control unit is designed to carry out the method as described above.

In the following, embodiments of the invention will be described with reference to the figures.

1 shows a schematic representation of a fluid pump system according to an embodiment of the invention.

2 shows a schematic representation of a fluid pump assembly of a fluid pump system according to an embodiment of the invention.

3 shows a schematic representation of a vehicle according to another embodiment of the invention.

4 shows a schematic representation of a family of characteristics of a fluid pump system according to another embodiment of the invention.

5 shows a schematic representation of the steps of a method according to another embodiment of the invention.

The illustrations in the figures are schematic and not to scale. If the same reference numbers are used, they refer to the same or similar elements.

1 shows a fluid pump system 10 with a first fluid pump arrangement 100 and a second fluid pump assembly 200 , The first fluid pump arrangement 100 is with a first fluid supply line 114 coupled and via a first fluid discharge 116 and a first check valve 11 with the common derivative 16 connected. The second fluid pump arrangement 200 is with a second fluid supply line 214 coupled and via a second fluid discharge 216 and a second check valve 12 with the common derivative 16 connected. The two fluid supply lines 114 . 214 are used in this embodiment as Zuleitungsanordnung 14 designated.

1 shows the two fluid pump assemblies 100 . 200 in a parallel operation. In this exemplary mode of operation, the fluid pump assemblies may be particularly configured such that both fluid pump assemblies have the same volume flow under the same fluid pressure in the fluid drains 116 . 216 deliver.

2 shows an example of a fluid pump assembly 100 with a pump device 105 , an energy source 130 , a control unit 140 and a storage unit 150 , It should be noted that this structure basically for both fluid pump assemblies 100 . 200 as in 1 may apply. This is also indicated by the fact that some elements in 2 are each provided with two reference numerals and corresponding to the first fluid pump arrangement ( 100 , 1xx) or the second fluid pump assembly ( 200 , 2xx) are assigned. The energy source 130 , the control unit 140 and the storage unit 150 can for any fluid pump assembly 100 . 200 can be provided individually, but these can also be present only once and the control of the first and second pump device 105 . 205 take. The following describes the elements with reference to the first fluid pump arrangement. It should be understood that these explanations apply analogously to the second fluid pump arrangement.

The pump device 105 has a pump unit 110 and a pump motor 120 on. The pump unit 110 and the pump motor may be arranged in a common housing or constitute a mounting unit. Anyway, the pump motor 120 designed as a DC motor and so with the pump unit 110 coupled so that the pump motor drives the pump unit to pump fuel by means of the pump unit.

It should be noted that the fluid pump arrangement 100 with reference to the figures in the application example of a fuel pump assembly is described. This description is for illustrative purposes only and is not intended to limit the scope of the claims to the use of the fluid pump assembly as a fuel pump assembly. The principles of operation set forth in the figures and the associated description are valid for any type of fluid pump. In the following, the terms of the fluid pump arrangement are related to a fuel pump arrangement.

The pump unit 110 is via a fuel supply line 114 directly or indirectly with a fuel tank (not shown) and via the fuel delivery 116 indirectly or directly connected to an internal combustion engine (not shown). Alternatively, the pump device 105 be arranged in the fuel tank.

The energy source 130 supplies a current of predeterminable current to the pump motor 120 , The speed of the pump motor changes with the current and a changed speed of the pump motor changes the pumping property of the pump unit so that a volume flow of the fuel from the fuel supply line 114 to the fuel discharge 116 and also the fuel pressure in the fuel delivery 116 changed. Thus, depending on the current strength of the pump motor 120 the fuel pressure in the fuel drain 116 be varied.

The control unit 140 is both with the energy source 130 as well as with the pump device 105 , in particular the pump motor 120 coupled, so the control unit 140 from the source of energy 130 Adjust the supplied current and the speed of the pump motor 120 determined or obtained.

The control unit 140 is still with the storage unit 150 coupled to those in the storage unit 150 read off stored or stored characteristics and to remove therefrom or to determine the set for a desired fuel pressure current.

3 shows a vehicle 1 with an internal combustion engine as drive unit 5 , a fuel tank 3 and a fluid pump system 10 such as in 1 shown. The fluid pump system 100 is arranged so that fuel through the supply line 14 and the common derivative 16 from the fuel tank 3 to the drive unit 5 is pumped.

4 shows a characteristic field in which three characteristics 112A . 112B . 112C are registered as isobaric characteristics. The characteristic curves are entered in a diagram, which shows the current strength 124 the pump motor 120 above the speed 122 the pump motor 120 applying. Every characteristic 112A . 112B . 112C corresponds in each case to a fuel pressure in the fuel discharge 116 , It should be noted that the characteristic curves in 4 are plotted linearly for illustrative purposes, but they may also have a different course depending on the respective fluid pump arrangement.

The characteristic 112A For example, the fuel pressure of 6 bar, the characteristic 112B a fuel pressure of 4 bar and the characteristic 112C correspond to a fuel pressure of 2 bar.

Operates the fuel pump at a current speed 123 and a pressure of 4 bar (ie at a current according to the characteristic 112B ) and a change of the fuel pressure to 2 bar is specified (this corresponds to the characteristic curve 112C ), so is called new current 125 the current according to the characteristic 112C at the current speed 123 taken from the characteristic field and output from the power source to the pump motor. Changes due to the changed current and the current pump motor speed 123 , so the changed current value according to the changed pump motor speed also from the characteristic 112C read, since this characteristic corresponds to the new predetermined fuel pressure. Thus, an iterative approach to the operating point for the given fuel pressure can be achieved.

The speed of the pump motor can be between 2500 and 8000 revolutions per minute. The pump current can be between 4 amps and 17 amps.

5 shows a schematic representation of the steps of a method according to an embodiment of the invention.

In a step S1, the specification of a target value for a fuel pressure in a fuel delivery takes place. In a following step S2, the determination of a current occurs 125 , which is a pump motor speed 123 is assigned and corresponds to the predetermined setpoint for the fuel pressure (ie, that a pair of values of amperage and pump motor speed are on an isobaric characteristic of the predetermined fuel pressure). In a following step S3 follows the output of the read current 125 to a DC pump motor 120 the fluid pump assembly 100 , In step S4, monitoring of the pump motor speed follows 123 and in step S5 adjusting the current 125 according to the characteristic curve, so that the setpoint for the fuel pressure in the fuel discharge 116 is set or maintained.

Steps S1 to S3 may again follow steps S4 and S5, so that the fuel pressure is iteratively approximated to its desired value if the pump motor speed also changes as a function of the changed current intensity.

LIST OF REFERENCE NUMBERS

1

 motor vehicle

3

 Fluid container / fuel tank

5

 drive unit

10

 Fluid pump system

11

 first check valve

12

 second check valve

14

 supply arrangement

16

 common derivative

100

 first fluid pump assembly / fuel pump assembly

105

 pump device

110

 pump unit

112

 Fuel pressure characteristic

114

 Fluid feed / fuel delivery

116

 Fluid discharge / fuel conductor

120

 pump motor

122

 Engine speed

124

 motor current

130

 energy

140

 control unit

150

 storage unit

200

 second fluid pump assembly / fuel pump assembly

Claims (13)

Fluid pump system ( 10 ), comprising: a first fluid pump assembly ( 100 ), which is designed, a fluid via a first fluid supply line ( 114 ) and via a first fluid discharge ( 116 ) a second fluid pump arrangement ( 200 ), which is carried out, a fluid via a second fluid supply line ( 214 ) and via a second fluid discharge ( 216 ) wherein the first fluid pump arrangement ( 100 ): a first pump device ( 105 ) with a first pump unit ( 110 ) and a first pump motor ( 120 ), wherein the first pump motor with the first pump unit ( 110 ) is coupled so that the first pump motor can drive the first pump unit; an energy source ( 130 ) to the first pump motor ( 120 ) with electricity; and a control unit ( 140 ); the control unit ( 140 ), a setpoint for one of the first pump device ( 105 ) to be supplied fluid pressure and at a predetermined pump motor speed the target value for the fluid pressure to be supplied corresponding current for the first pump motor ( 120 ) and the energy source ( 130 ) so that it reaches the determined current intensity to the first pump motor ( 120 ). Fluid pump system ( 10 ) according to claim 1, wherein the first fluid discharge ( 116 ) and the second fluid discharge ( 216 ) are coupled in a common derivation ( 16 ); wherein the first fluid pump arrangement ( 100 ) via a first check valve ( 11 ) with the common derivative ( 16 ) is coupled; wherein the second fluid pump arrangement ( 200 ) via a second check valve ( 12 ) with the common derivative ( 16 ) is coupled. Fluid pump system ( 10 ) according to claim 1 or 2, wherein the second fluid pump arrangement ( 200 ) comprises: a second pumping device ( 205 ) with a second pump unit ( 210 ) and a second pump motor ( 220 ), wherein the second pump motor with the second pump unit ( 210 ) is coupled so that the second pump motor can drive the second pump unit; the energy source ( 130 ), the second pump motor ( 220 ) with electricity; and wherein the control unit ( 140 ), a setpoint for one of the second pump device ( 205 ) to be supplied fluid pressure and at a predetermined pump motor speed to the setpoint for the fluid pressure to be delivered corresponding current for the second pump motor ( 220 ) and the energy source ( 130 ) in such a way that this determines the determined current intensity to the second pump motor ( 220 ). Fluid pump system ( 10 ) according to one of the preceding claims, further comprising a memory unit ( 150 ), wherein the memory unit ( 150 ), a current-speed characteristic ( 112A ) of the first pump motor ( 120 ), wherein the current-speed characteristic curve of one of the first pump unit ( 110 ) corresponds to delivered fluid pressure. Fluid pump system ( 10 ) according to claim 4, wherein the memory unit ( 150 ) is executed, a plurality of current-speed characteristics ( 112A . 112B . 112C ) of the first pump motor ( 120 ), wherein each of the current-speed characteristics in each case one of the first pump unit ( 110 ) corresponds to delivered fluid pressure. Fluid pump system ( 10 ) according to one of claims 4 or 5, wherein the control unit ( 140 ), the pump motor speed ( 123 ) of the first pump motor ( 120 ) to investigate; the control unit ( 140 ), the energy source ( 130 ) to control the current at which the first pump motor ( 120 ) is adjusted according to the characteristic so that the target value for the fluid pressure supplied by the first pump device is adjusted or maintained. Method for controlling a fluid pump system ( 10 ) according to one of claims 1 to 6, comprising the following steps: predetermining (S1) a nominal value for a fluid pressure in the first fluid discharge ( 116 ); Determining (S2) a current ( 125 ), which corresponds to a pump motor speed ( 123 ) of the first pump motor ( 120 ) and corresponds to the predetermined setpoint for the fluid pressure; Output (S3) of the read current ( 125 ) to the first pump motor ( 120 ) of the first fluid pump arrangement ( 100 ). The method of claim 7, wherein determining the amperage ( 125 ), which is the pump motor speed ( 123 ) of the first pump motor ( 120 ), comprising the step of: reading the current ( 125 ) from a characteristic curve ( 112C ), which corresponds to the predetermined setpoint for the fluid pressure. The method of claim 8, further comprising the steps of: monitoring (S4) the pump motor speed ( 123 ) of the first pump motor ( 120 ); Adjusting (S5) the current ( 125 ) according to the characteristic curve ( 112C ), so that the setpoint for the fluid pressure in the first fluid discharge ( 116 ) is set or maintained. Method according to one of claims 7 to 9, further comprising the steps of determining a respective pump motor speed-current characteristic ( 112A . 112B . 112C ) for a plurality of target values of the fluid pressure in the fluid discharge; Providing the characteristics thus determined in order to match a pump motor speed ( 123 ) associated current ( 125 ) read out at a predetermined setpoint of the fluid pressure. Vehicle ( 1 ) with a fluid pump system ( 10 ) according to one of claims 1 to 6, wherein the fluid pump system ( 10 ) is designed as a fuel pump arrangement. Vehicle according to claim 11, wherein the fluid pump system ( 10 ) with a fuel tank ( 3 ) and is adapted to a fuel contained in the fuel tank to a drive unit ( 5 ) of the vehicle. Vehicle ( 1 ) according to claim 11 or 12, wherein the control unit ( 140 ) is executed to carry out the method according to one of claims 7 to 10.

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